Island



(No Model.) 2 Sheets- Sheet 1.

G. D. ROGERS. I

ROLLED WOOD SCREW.

No. 438,754. Patented Oct. 21, 1890.

FIE-E- INVENTOR- (No Model.) 2 Sheets-Sheet 2.

G. D. ROGERS.

ROLLED WOOD SCREW.

No. 438,754. Patented Oct. 21, 1890.

N V E N TuR. Chem a} 3mm.

WITNESSES.

UNITED STATES PATENT CHARLES D. ROGERS, OF PROVIDENCE, RHODE ISLAND,ASSIGNOR TO THE AMERICAN SCREW COMPANY, OF SAME PLACE.

ROLLED WOOD-SCREW.

SPECIFICATION forming part of Letters Patent No. &38,754, dated October21, 1890.

Application filed August 4, 1890. Serial No. 360,863. (Nomodeh) To allwhom it may concern.-

Be it known that I, CHARLES D. ROGERS, a citizen of the United States,residing at Providence, in the county of Providence and State of RhodeIsland, have invented certain new and useful Improvements inWood-Screws; and I do hereby declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same,reference being had to the accompanying drawings, and to letters ofreference marked thereon, which form a part of this specification.

In the manufacture of wood-screws it is now, as well as for some yearspast, the almost universal practice to provide such screws with what istermed a gimlet-pointthat is, screws adapted to be inserted into woodwithout the necessity of first boring a hole into the wood for thescrew. This type of screw is not confined alone to cut screws-that is,screws in which a spiral groove is cut into the blanks body to produce athread by the aid of a eutting-toolbutit also includes the more modern,or rolled screw, as it is termed. The latter are in some instancesproduced by introducing the blanks cold between apair ofoppositely-traveling dies having their working-faces provided with aseries of inclined grooves and ribs. The action of these grooves andribs is to roll a spiral groove or crease nto the blanks shank portion,the displaced metal being at the same time gradually transformed into araised rib or thread having a suitable form cross-sectionally. Sometimesthe threads of a rolled screw are produced without an appreciableelongation of the blank, the thread then being considerably larger indiameter than the normal size of the blank. Again, the screw iselongated and not enlarged laterally by the rolling process, thediameter of the threaded and unthreaded portions being alike, andsometimes the screws are both enlarged and elongated by the action ofthe dies to which they are subjected. I believe that in each of themethods of rolling just referred to the point portion of screws thusproduced are to a great extent i mperfectly screw-threaded.

I have discovered that it is not necessary that a rolled screw shallhave a screw-threaded point in order to readily enter it into wood, onereason being that the metal now used is more homogeneous or less fibrousthan that formerly employed. Therefore the thread can be made thinnerand consequently sharper,

so that it is more easily inserted, because the edge of the threadreadily cuts the wood as the screw is advanced into it. This latterfeature is especially noticeable when the threads are produced by myimproved dies, which form a solid thread, as clearly described in aUnited States Patent granted to me September 20, 1887, and numbered370,354.

The improved wood-screw forming the subject of my present applicationdiffers fromothers of its class in that it has an unthreaded sharpenedor cone-shaped centering end or tip formed on its point portion adaptedto be inserted into wood by a slight blow. The point portion is alsoprovided with oppositelyarranged screw-threads, commencing at the baseof the tip, which extend radially and form chisel-shaped or cuttingedges. From this point the two threads extend rearwardly along theblanks body any desired distance, the screw terminating at the adjacentend in an enlarged head, provided with a slot or other suitable form bywhich the screw is adapted tobe inserted in the'wood. The unthreadedportion of the body of the screw uniting thehead and threaded portion Iprefer to make slightly tapering or conical, thereby increasing itsstrength.

An advantage of my improvement is that in inserting the screw theunthreaded tip serves to first center and steady or support the screwlaterally, after which the sharpened or chisel-pointed end of the twothreads act to cut their way readily into the wood. By the employment ofthe double thread the work or resistance opposed .to the entrance of thescrew is equalized at all points, so that it is more easily and trulyintroduced than screws having a single thread and unprovided with thesharpened tip and chisel-shaped thread terminations.

In the appended two sheets of drawings, Figure 1 represents a sideelevation of the headed screw blank before being screwthreaded and asmade from wire, aportion of its upper portion beingbroken away. Fig. 2is a similar View of the blank after being screwthreaded and forming myimproved rolled wood-screw. Fig. 3 is an inverted end view, enlarged, ofthe screw. Fig. 4 is a plan view. Fig. 5, Sheet 2, is a side view of thelower portion of a blank having its spur orentering end polygonal orpyramidal shaped. Fig. 6 is a similar View of the blank shown in Fig. 5after being screw-threaded; and Fig. -7 is an invented end view,enlarged, showing modified forms of the pyramidal point.

In the drawings, 1) indicates the blank as a whole, consisting of theheaded portion h, an enlarged or tapering shank portion 8, thecylindrical shank portion 8, and the point portion p, the latterprovided with a comparatively blunt part 99 extending from the plainportion 8 and terminating in a sharpened tip 19, having the inclinationof its sides more acute than those of the proximate portion 10 Theblanks are made singly from a con tinuone length of wire whose normaldiameter is substantially the same as that of the cylindrical part 8,the head h and enlarged portion 3' being formed simultaneously byupsetting the metal in a suitable die by means of a heading-machine. Thenick n may also be produced at the same time. The headed wire is nextforced out of the die and fed ahead the desired distance to produce ablank, after which properly-shaped cutting-oif dies conjointly sever theblank from the wire and form the point portion 19. The blanks b are nextintroduced to a machine which forms the double screw-threads 25 upon thebody of the blank by rolling it between dies, which force the metal toexpand radially into grooves in the die, which give the form requiredfor the threads, the completed screw being indicated by a, Fig. 2. Itwill be noticed that the diameter of the threaded portion t issubstantially the same as the diameter of the enlarged plain portion 5of the shank at its junction with the head h, as indicated by theparallel dotted lines 0. The screw-threads terminate practically aboutmidway of the point portion p, or at the intersection of the parts p andp, in oppositelyarranged sharpened edges t. (See Figs. 2 and 3.) Thesesharpened or chisel-shaped edges are first to enter the wood (after theintroduction of the spur p) and readily cut their way through it as thescrew is advanced (see arrow direction) by the aid of the driver. Thefull efficiency or holding capacity of the screw a is thus obtained, itbeing well known that a screw threaded to the extreme end of' aconeshaped point adds nothing to its holding powers.

It is obvious that the sharpened or spurshaped tip 19' may have apyramidal form, substantially as represented by Figs. 5, 6, and 7, inlieu of the conical form shown by the other figures, without departingfrom the spirit of the invention. In-such case the blanks, Fig. 5, arecut olf by means of dies having a correspondingly-shaped cavity.

I would further state that if the point be extended, as indicated bydotted lines in Fig. 1, then thepoint 19 would be too blunt to serve oneof the purposes required, or, in other words, the resistance to enteringthe wood would be too great, whereas the spur-point portion 19' servesto overcome the objections by having a more acute angle. Anotheradvantage of the double angle .formed on the point portion of the blank(see Fig. 1) is that the part 19 having a less acute angle, isessential, in order to provide the amount of metal necessary to betransformed into the enlarged threads on the point as compared with anordinary rolled wood-screw havinga screw-threaded point-that is to say,if the sides of the point formed a true cone then the metal taken toproduce the thread would leave the contiguous sides more acute than theentering end, which is undesirable. Prac tically by first making thesides of the point p of the blank substantially as represented in Fig.1, the root of the't-hread when formed thereon will then besubstantially a continuation of the sides forming the entering portion1). (See Fig. 2.) By means of such construction it will be observed thatare-entrant angle '1' is formed in the blank at the intersection of thetwo parts 10 10, forming the point portion, which angle practicallydisappears when the thread is produced. (See Fig. 2.)

I claim.

l. A screw with the thread of the cylind'rical portion extended onto theconical surface of the point, but reduced in diameter to correspond withthe diameter of such surface and terminating in a cutting-edge beforethe extreme point is reached.

a 2. A wood-screw having the threads of the cylindrical portion extendedonto the surface of the point portion, but reduced in diameter tocorrespond with the diameter of such surface,and terminating in acutting-edge, and having an unthreaded spur shaped entering portion 19',substantially as hereinbefore described.

In testimony whereof I have afiixed my signature in presence of twowitnesses.

CHARLES 'D. RD GERS.

Witnesses:

CHARLES HANNIGAN, GEO. H. REMINGTON.

